City T and City U are 576 km apart. At 4.59 p.m., Charlie is travelling at a uniform speed left City T for City U while Andy set off from City U to City T along the same road at a uniform speed, which was 12 km/h slower than that of Charlie. The two met at 7.59 p.m.
- Find the speed of Charlie.
- If Andy continued to travel at the same speed, how long would it take for him to reach his destination after the two met? Express your answer in mixed number.
(a)
Time taken for Charlie and Andy to travel from 4.59 p.m. to 7.59 p.m. = 3 h
Average speed of Charlie and Andy
= 576 ÷ 3
= 192 km/h
Charlie's speed
= (192 + 12) ÷ 2
= 204 ÷ 2
= 102 km/h
(b)
Andy's speed
= 102 - 12
= 90 km/h
Distance that Andy travelled in 3 h
= 3 x 90
= 270 km
Remaining distance that Andy needed to travel
= 576 - 270
= 306 km
Time that Andy needed to reach his destination after the two met
= 306 ÷ 90
= 3
3690 = 3
25 h
Answer(s): (a) 102 km/h; (b) 3
25 h